Abstract

We experimentally demonstrate the generation of nondegenerate nonclassical paired photons in a hot atomic ensemble using off-axis four-wave mixing. The time-resolved second-order correlated function between the Stokes photon and the anti-Stokes photon is given. The two-photon correlation between the photons obtained in this experiment is 1.87±0.04, which leads to the violation of Cauchy-Schwarz inequality by a factor of 1.69±0.14.

Figures (4)

Schematic setup of this experiment. Left, Energy levels of 87Rb, and the frequency arrangement of the lasers used in this experiment, where |1〉 and |2〉 are the hyperfine sublevels of the ground state, and |3〉 and |4〉 are excited states. Right, experimental setup. A strong coupling laser and a weak pump laser with orthogonal linear polarization counter propagate through a rubidium cell. Paired Stokes and anti-Stokes photons are generated in phase-matched directions. These photons are collected by single-mode fibers and detected by single photon counting modules. F1 and F2 are filters, each consists of a polarizer, an optical pumped Rb cell and a ruled diffraction grating.

The time-resolved coincidences between the fields versus time delay τ with the powers of the coupling and pump of 7.0 mW and 40 µW, respectively. All the data are normalized in time. (a) the coincident statistics between the Stokes photons and the anti-Stokes photons is shown. Data are collected over 1000 seconds. (b) and (c) show the self-coincidence of the Stokes photons and the anti-Stokes photons. Data are collected over 15000 and 3000 seconds respectively. cell, the quick moving out of and into the coupling